Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Proc Natl Acad Sci U S A. 2011 Jun 14;108(24):9863-8. doi: 10.1073/pnas.1018493108. Epub 2011 May 31.
Lineage progression in osteoblasts and chondrocytes is stringently controlled by the cell-fate-determining transcription factor Runx2. In this study, we directly addressed whether microRNAs (miRNAs) can control the osteogenic activity of Runx2 and affect osteoblast maturation. A panel of 11 Runx2-targeting miRNAs (miR-23a, miR-30c, miR-34c, miR-133a, miR-135a, miR-137, miR-204, miR-205, miR-217, miR-218, and miR-338) is expressed in a lineage-related pattern in mesenchymal cell types. During both osteogenic and chondrogenic differentiation, these miRNAs, in general, are inversely expressed relative to Runx2. Based on 3'UTR luciferase reporter, immunoblot, and mRNA stability assays, each miRNA directly attenuates Runx2 protein accumulation. Runx2-targeting miRNAs differentially inhibit Runx2 protein expression in osteoblasts and chondrocytes and display different efficacies. Thus, cellular context contributes to miRNA-mediated regulation of Runx2. All Runx2-targeting miRNAs (except miR-218) significantly impede osteoblast differentiation, and their effects can be reversed by the corresponding anti-miRNAs. These findings demonstrate that osteoblastogenesis is limited by an elaborate network of functionally tested miRNAs that directly target the osteogenic master regulator Runx2.
成骨细胞和软骨细胞中的谱系进展受到细胞命运决定转录因子 Runx2 的严格控制。在这项研究中，我们直接探讨了 microRNAs（miRNAs）是否可以控制 Runx2 的成骨活性并影响成骨细胞成熟。一组 11 种 Runx2 靶向 miRNAs（miR-23a、miR-30c、miR-34c、miR-133a、miR-135a、miR-137、miR-204、miR-205、miR-217、miR-218 和 miR-338）在间充质细胞类型中以谱系相关的模式表达。在成骨和成软骨分化过程中，这些 miRNA 通常与 Runx2 呈负相关表达。基于 3'UTR 荧光素酶报告基因、免疫印迹和 mRNA 稳定性测定，每种 miRNA 都直接减弱了 Runx2 蛋白的积累。Runx2 靶向 miRNAs 以不同的效率在成骨细胞和软骨细胞中抑制 Runx2 蛋白表达。因此，细胞环境有助于 miRNA 对 Runx2 的调节。所有 Runx2 靶向 miRNAs（除了 miR-218）都显著抑制成骨细胞分化，并且它们的作用可以通过相应的反义 miRNA 逆转。这些发现表明，成骨细胞发生受到功能测试的 miRNAs 的精细网络限制，这些 miRNAs 直接靶向成骨主调节因子 Runx2。
